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c64447a929
All the daemons will use a common seed for point derivation, so drag it out of lightningd/opening. This also provide a nice struct wrapper to reduce argument count. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
62 lines
1.8 KiB
C
62 lines
1.8 KiB
C
#include <ccan/crypto/hkdf_sha256/hkdf_sha256.h>
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#include <ccan/crypto/sha256/sha256.h>
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#include <ccan/crypto/shachain/shachain.h>
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#include <lightningd/derive_basepoints.h>
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#include <utils.h>
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bool derive_basepoints(const struct privkey *seed,
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struct pubkey *funding_pubkey,
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struct basepoints *basepoints,
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struct secrets *secrets,
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struct sha256 *shaseed,
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struct pubkey *per_commit_point,
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u64 per_commit_index)
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{
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struct sha256 per_commit_secret;
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struct keys {
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struct privkey f, r, p, d;
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struct sha256 shaseed;
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} keys;
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hkdf_sha256(&keys, sizeof(keys), NULL, 0, seed, sizeof(*seed),
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"c-lightning", strlen("c-lightning"));
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secrets->funding_privkey = keys.f;
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secrets->revocation_basepoint_secret = keys.r;
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secrets->payment_basepoint_secret = keys.p;
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secrets->delayed_payment_basepoint_secret = keys.d;
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if (!pubkey_from_privkey(&keys.f, funding_pubkey)
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|| !pubkey_from_privkey(&keys.r, &basepoints->revocation)
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|| !pubkey_from_privkey(&keys.p, &basepoints->payment)
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|| !pubkey_from_privkey(&keys.d, &basepoints->delayed_payment))
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return false;
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/* BOLT #3:
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*
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* A node MUST select an unguessable 256-bit seed for each connection,
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* and MUST NOT reveal the seed.
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*/
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*shaseed = keys.shaseed;
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/* BOLT #3:
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*
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* the first secret used MUST be index 281474976710655, and then the
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* index decremented. */
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shachain_from_seed(shaseed, 281474976710655ULL - per_commit_index,
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&per_commit_secret);
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/* BOLT #3:
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*
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* The `per-commitment-point` is generated using EC multiplication:
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*
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* per-commitment-point = per-commitment-secret * G
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*/
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if (secp256k1_ec_pubkey_create(secp256k1_ctx,
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&per_commit_point->pubkey,
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per_commit_secret.u.u8) != 1)
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return false;
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return true;
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}
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